The present invention is especially useful in connection with automatic sprinkler systems in places where temperature changes are expected at which water will freeze. The system generally provides for a frangible membrane across the water supply pipe at the beginning of the portions of the system subject to freezing, with an antifreeze liquid downstream of the membrane. The frangible membrane is suitably mounted to one end of a bellows so that it can move freely to some degree without rupturing. Such movement is necessary in order to compensate for small, inevitable changes in solute volume.
Heretofore valves of one kind or another have been used to separate out the water from the antifreeze in systems of this kind.
Livingston U.S. Pat. No. 3,871,457 shows a fluid control device that obviously operates on a different principle from that here contemplated. Ryder U.S. Pat. No. 2,340,144 likewise has an arrangement that could be used in such context as the present device but also requires the operation of a valve. Other patents of a similar nature are U.S. Pat. Nos. 1,765,840, 945,956 and 953,260, which involve the presence of valves of one kind or another, all of which are subject to leaking or to becoming locked into one position or another by the presence of corrosion, fatigue or the like.